Problem: Graph this system of equations and solve. $5x-4y = -4$ $-2x+8y = -24$ $1$ $2$ $3$ $4$ $5$ $6$ $7$ $8$ $9$ $10$ $\llap{-}2$ $\llap{-}3$ $\llap{-}4$ $\llap{-}5$ $\llap{-}6$ $\llap{-}7$ $\llap{-}8$ $\llap{-}9$ $\llap{-}10$ $1$ $2$ $3$ $4$ $5$ $6$ $7$ $8$ $9$ $10$ $\llap{-}2$ $\llap{-}3$ $\llap{-}4$ $\llap{-}5$ $\llap{-}6$ $\llap{-}7$ $\llap{-}8$ $\llap{-}9$ $\llap{-}10$ Click and drag the points to move the lines.
Answer: Convert the first equation, $5x-4y = -4$ , to slope-intercept form. $y = \dfrac{5}{4} x + 1$ The y-intercept for the first equation is $1$ , so the first line must pass through the point $(0, 1)$ The slope for the first equation is $\dfrac{5}{4}$ . Remember that the slope tells you rise over run. So in this case for every $5$ positions you move up You must also move $4$ positions to the right. $4$ positions to the right. $5$ positions up from $(0, 1)$ is $(4, 6)$ Graph the blue line so it passes through $(0, 1)$ and $(4, 6)$ Convert the second equation, $-2x+8y = -24$ , to slope-intercept form. $y = \dfrac{1}{4} x - 3$ The y-intercept for the second equation is $-3$ , so the second line must pass through the point $(0, -3)$ The slope for the second equation is $\dfrac{1}{4}$ . Remember that the slope tells you rise over run. So in this case for every $1$ position you move up You must also move $4$ positions to the right. $4$ positions to the right. Graph the green line so it passes through $(0, -3)$ and $(4, -2)$ The solution is the point where the two lines intersect. The lines intersect at $(-4, -4)$.